Unicode

If 2 code units, first one is in 0xD800-0xDBFF, second one is in 0xDC00-0xDFFF.

First one: 6 fixed bits (0b110110) then 4 bits encoding the Unicode plan (minus one: 1-16 become 0-15) then 6 first bits from inside the plan - note that the plan number is splitted between the two last bits of the first byte and the two first bits of the second byte

Second one: 6 fixed bits (0b110111) then 10 last bits from inside the plan